Purification and some properties of proteinase fromPseudomonas fluorescensNo. 33

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Abstract
Summary: The extracellular proteinase fromPseudomonas fluorescensNo. 33 was purified to electrophoretic homogeneity by a procedure including precipitation with HC1 and (NH4)2SO4, and column chromatography. The enzyme was purified 170-fold giving a yield of 7 % of the original activity. The molecular mass of the purified enzyme was 48000 by SDS-PAGE. The optimum pH and temperature for the hydrolysis of casein were 8·0–9·8 and 30–35 °C respectively. The enzyme was more thermostable in synthetic milk salts solution than in 0·1 M-sodium phosphate buffer, but was heat-labile at 50 °C in both buffer Systems. The activity was inhibited byo−phenanthroline, Hg2+, Cu2+, Fe2+and, to a lesser extent, Ni2+. Caseins were susceptible to the proteinase, but degradation patterns were dependent on the form of the casein.